Insulating joint for electric cables



May 3, 1938. H, HORN 2,116,266

INSULATING JOINT FOR ELECTRIC GABLES Filed Jan. 50, 1956 Fig. I

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Patented May 3, 1938 UNITED STATES PATENT OFFICE INSULATING JOINT FOR ELECTRIC CABLES Heinz Hem, Nordenham, Germany, assignor to Norddeutsche Seekabelwcrke A. G., Nordenham,

Germany Application January so, 1936, Serial No. 61,615 In Germany February 4, 1935 4 Claims.

This invention relates to a method of and apparatus for producing joints in the insulation of cables, more particularly submarine cables 'which are insulated with a thermoplastic substance, the

invention being applicable to any kind of thermothat after the insulating ends have beensuitably prepared, they are caused to overlap under heat,

can be carried out successfully only by suitable specialized workmen. The difl'lculty to overcome consists in effecting all the numerous insulating joints of a. submarine cable equally well, so that none of the many hundreds of overlapping places shall have a capillary break, through which the water couldpass, sooner or later.

The invention mainly relates to a method which enables a seamless joint to be produced. The invention further relates to an apparatus for carrying out this process. The'invention will hereinafterbe described with reference tothe drawing, which illustrates, by way of example, one modeof carrying the invention into effect, the reference letters and numerals denoting the same parts in the various figures.

The two conductor ends II and I! to be connected together are first of all treated in such a -manner that the thermoplastic insulating material b is pushed back from the copper conductor a while being heated, so that a large thickening 0 is formed in the insulating covering and a long portion of the copper conductor is laid bare. Thereupon a long portion of the bared copper conductor is cut off; the bare conductors which and I which are secured to a support IS. -The apparatus l6 for the production of the joint is mounted on a frame 'l1 which can be moved along the conductors by means of a handle operated drive It. Alternatively, the conductors may be pulled' through the stationary pair of rolls.

The apparatus I6 is illustrated in detail in Figures 2 and 3. It mainly consists of the rolls l9 and provided in the middle with a recess 25. This recess is of such a size that it surrounds the insulated conductors, exactly conforming thereto. The rolls rotate in the direction of the arrows indicated in Figure 2. The pair of rolls is mounted in a casing 2|, which closely surrounds the conductors, so that no insulating substance can pass through the rolls; thescrapers 22 resting on the rolls serve for the samepurpose. The apparatus I6 is so constructed that the upper part with the roll Hi can be turned over or be removed, in order to insert the conductor or take it out.

The insulating joint is produced asfollows: The insulation 17, including the thickened portion 0, is heated to the temperature necessary to render the insulating material plastic, e. g. by means of a jet of steam or spirit flame (not shown in the drawing). At the same time, the pair of rolls I9, 20 is set into rotation by hand by means of the handle 24, or by means of a motor, and the whole of the apparatus I6 is moved from left to right, for instance, by tuming the handle 23 (Figure 1). -As soon as the pair of rolls reaches the thickened portion, the heated insulating mass is thoroughly kneaded, in the same way as in the case of the known mills for rolling rubber miktures.

The construction of the casing I6 and the scrapers 22 prevent any insulating material from passing through the rolls.

vAs the apparatus I5 is further moved, the pair of rolls I9, 20 reaches also the second thickened portion 0 which has been heated in the meantime, and the insulating material at this point is thoroughly kneaded together withthe remainder of the insulating material of the first thickened portion, so that a perfectly homogeneous mass is obtained which is shaped to the normal crosssection of the conductor by the recess in the rolls and the internal diameter of the casing 2|. After the actual union of the two ends of the insulation has been effected in this way, the heating of the insulation is interrupted and the rolling apparatus I 6 is moved along the conductor, until the rolls come to lie in a place where they are no longer heated. The casing of the rolling apparatus is then opened, any possible traces of insulating material are removed and the completed joint is taken out.

sulation. If desired, use may naturally be made,

to a more or less great extent, of fresh insulating material, which is kneaded with the available material to form an integral mass, by means of the mixing pair of rolls. If found advantageous for special reasons, the production of the joint may also be effected, by forming a thickening on the insulation, only on one of the two conductor ends, and therefrom building upthe insulation over the soldered point of the copper in the manner above described.

What I claim is:

l. A method of producing a seamless joint in the insulation of electric cables which are insulated with thermoplastic substances, consisting in that the two ends of the insulation to be connected together are softened and kneaded together on the conductor.

2. A method of producing a seamless joint in the insulation of electric cables which are insulated with thermoplastic substances, consisting in that the insulation is pushed back on the ends of the conductors to be connected together and thickenings thereof are thereby formed at a suitable distance from the ends of the conductors, that the conductors are then shortened and the connection between them efiected in a known manner, and that the said thickenings of the insulation are softened and kneaded together by rolling.

3. A method of producing a seamless joint in the insulation of electric cables which are insulated with thermoplastic substances, consisting in that the insulation is pushed back on the ends of the conductors to be connected together and thickenings thereof are thereby formed at a suit able distance from the ends of the conductors, that the conductors are then shortened and the connection between them eifected in a known manner and that the said thickenings of the insulation are softened and kneaded together by rolling along the joint.

4. A method of producing a seamless joint in the insulation of electric cables which are insulated with thermoplastic substances, consisting in that the insulation is pushed back on the ends of the conductors to be connected together and thickenings thereof are thereby formed at a suitable distance from the ends of the conductors, that the conductors are then shortened and the connection between them effected in a known manner and that the said thickenings of the insulation are then softened and kneaded together by rolling while adding fresh insulating material during the kneading.

HEINZ HORN. 

